That is why "guarantee" is in quotes. Any OS worth its salt should end up caching a "massively read" 4mb file (unless you are running on an OS with 1mb or memory). If the file was 400mb, you probably have a different story.
I welcome (and would hope) others to run the tests on various OSs and various hardware configs. I would expect similar results on other platforms, as most of the improvement is due to keeping the machine in user context and avoiding context switches to OS level code. -----Original Message----- From: John Haxby [mailto:[EMAIL PROTECTED] Sent: Friday, December 09, 2005 4:24 AM To: java-dev@lucene.apache.org Subject: Re: NioFile cache performance Robert Engels wrote: > Using a 4mb file (so I could be "guarantee" the disk data would be in > the OS cache as well), the test shows the following results. Which OS? If it's Linux, what kernel version and distro? What hardware (disk type, controller etc). It's important to know: I/O (and caching) is very different between Linux 2.4 and 2.6. The choice of I/O scheduler can also make a significant difference on 2.6, depending on the workload. The type of disk and its controller is also important -- and when you get really picky, the mobo model number. I don't dispute your finding for a second, but it would be good to run the same test on other platforms to get comparative data: not least because you can get the kind of I/O time improvement you're seeing on some workloads on different versions of the Linux kernel. jch --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
